Higher Chemistry

• Esters are formed by the condensation reaction between an alcohol and a carboxylic acid. This is known as esterfication.
• Esters are insoluble in water
• The functional group -COO is known as the ester link
• To make an ester a hydrogen atom must be removed from the hydroxyl group of the alcohol
• The breaking of an ester can be achieved by heating the ester with an alkali such as sodium hydroxide. A water molecule is added to break up the structure
• All fats and oils are naturally occuring esters formed by condensation reaction between the alcohol glycerol and different long chain carboxylic acids.
• Oils contain more carbon to carbon double bonds than fats making them have a lower melting point.
• Fats are solid at room temperature because they contain many single covalent bonds which hold the fatty acid chains together
• industrial scientists carry out different roles to maximise the efficiency of industrial processes and minimise the impact on the environment
• Chemical engineers focus on the design, operation and control of chemical processes used to turn raw materials into everyday and specialised products. Chemical engineers are responsible for selecting the best synthetic route to make a desired product, ensuring that reactions conditions are efficient, and driving down the energy costs.
• Production chemists are responsible for the operation for the operation of industrial processes. As a production chemist, you would use your knowledge of chemistry to monitor how raw materials are used to give the desired products.
• Environmental chemists monitor the impact of industrial processes on the environment
• Factors which influence the success or failure of a chemical process are availability/sustainability and cost of feedstock. as well as opportunities for recycling, energy requirements, use of by products and yield of product
• two reactions conditions which should be controlled in order to maximise the efficiency of a chemical process. These are temperature and pressure.
• Heat loss to the surrounding can be minimised by using insulation
• Heat exchangers are widely used in industrial processes to transfer heat between two fluids at different temperatures.
• The key principles of green chemistry are reactants, process and environment.
• An exothermic reaction is ones is which heat energy is released to the surroundings
• in an exothermic reaction enthalpy change is negative
• An endothermic reaction is one in which heat energy is taken in from the surroundings.
• The enthalpy change for an endothermic reaction is positive
• The enthalpy of combustion is the energy released when one mole of a substance burns completely in oxygen.
• Any difference between the standard enthalpy of combustion and the experimental enthalpy of combustion in part may be due to the experimental data not being done in a sealed system.
• The enthalpy of solution is the enthalpy change when one mole of substance dissolves in water.
• The enthalpy of neutralisation of an acid is the enthalpy change when the acid is neutralised to form one mole of water.
• The standard enthalpy of combustion is enthalpy change when one mole of a substance burn completely at standard temperature and standard pressure
• The standard enthalpy of formation is the enthalpy change when one mole of a substance is formed from its elements in their standard states at standard conditions
• Hess's Law states that the enthalpy for a reaction is independent of the route taken.
• The bond enthalpy is the energy required to break one moles of bond between the atoms in one mole of gaseous diatomic molecules, at standard conditions
• Bond breaking is endothermic
• Bond forming is exothermic
• The enthalpy of a reaction is the difference between the energy needed to break the bonds in the reactants and the energy released when bonds are formed in the products.
• The name of the digestion process where enzymes break down proteins into amino acids is called hydrolysis
• proteins are polymers made up of a chain of small monomers known as amino acids.
• amino acids are small molecules which contain at least two functional groups
• essential amino acids are amino acids which cannot be made by the body and must be obtained through diet
• amino acids are joined together in a condensation reaction
• uv light can provide enough energy to break some covalent bonds within molecules.
• free radicals are atoms or molecules that are highly reactive due to the presence of unpaired electrons.
• the three stages of a free radical chain reaction are initiation, propagation and termination